Null type¶
-
class
pyasn1.type.univ.
Null
(value=NoValue(), tagSet=TagSet())¶ Create Null type or object.
Null objects are immutable and duck-type Python
str
objects (always empty).Parameters: - value (
str
orNull
object) – Python empty string literal or Null class instance. - tagSet (
TagSet
) – Object representing non-default ASN.1 tag(s)
Raises: : :py:class:`pyasn1.error.PyAsn1Error` – On constraint violation or bad initializer.
Note
The Null type models ASN.1 NULL.
-
clone
(value=NoValue(), tagSet=TagSet())¶ Create a copy of a Null type or object.
Any parameters to the clone() method will replace corresponding properties of the Null object.
Parameters: - value (
str
or Null object) – Initialization value to pass to new ASN.1 object instead of inheriting one from the caller. - tagSet (
TagSet
) – Object representing ASN.1 tag(s) to use in new object instead of inheriting from the caller
Returns: Null
– new instance of NULL type/value- value (
-
subtype
(value=NoValue(), implicitTag=Tag(), explicitTag=Tag())¶ Create a copy of a Null type or object.
Any parameters to the subtype() method will be added to the corresponding properties of the Null object.
Parameters: - value (
int
,str
or Null object) – Initialization value to pass to new ASN.1 object instead of inheriting one from the caller. - implicitTag (
Tag
) – Implicitly apply given ASN.1 tag object to caller’sTagSet
, then use the result as new object’s ASN.1 tag(s). - explicitTag (
Tag
) – Explicitly apply given ASN.1 tag object to caller’sTagSet
, then use the result as new object’s ASN.1 tag(s).
Returns: Null
– new instance of NULL type/value- value (
-
tagSet
= TagSet((), Tag(tagClass=0, tagFormat=0, tagId=5))¶ Default
TagSet
object for ASN.1 Null objects
-
hasValue
()¶ Indicate if Null object represents ASN.1 value or ASN.1 type.
The PyASN1 type objects can only participate in types comparison and serve as a blueprint for serialization codecs to resolve ambiguous types.
The PyASN1 value objects can additionally participate to most of built-in Python operations.
Returns: bool
–True
if object is ASN.1 value,False
otherwise.
-
isSameTypeWith
(other, matchTags=True, matchConstraints=True)¶ Examine Null type for equality with other ASN.1 type.
ASN.1 tags (
tag
) and constraints (constraint
) are examined when carrying out ASN.1 types comparison.No Python inheritance relationship between PyASN1 objects is considered.
Parameters: other (a pyasn1 type object) – Class instance representing ASN.1 type. Returns: bool
–True
if other is Null type,False
otherwise.
-
isSuperTypeOf
(other, matchTags=True, matchConstraints=True)¶ Examine Null type for subtype relationship with other ASN.1 type.
ASN.1 tags (
tag
) and constraints (constraint
) are examined when carrying out ASN.1 types comparison.No Python inheritance relationship between PyASN1 objects is considered.
Parameters: other (a pyasn1 type object) – Class instance representing ASN.1 type. Returns: bool
–True
if other is a subtype of Null type,False
otherwise.
- value (